US1893780A - Electric regulator - Google Patents

Description

Jan. 10, 1933. T. LY MAN, JR 1,893,780

ELECTRIC REGULATOR Filed April 17, 1931 l5 I "gas A: |4 no 1 I I 2v I 233 m 5 m 34 23 f l 1' r 1 3e, are/[ n 39 \48 W? H v v IO Inventor": Haroid T Lgman Jn y flaw/m His Attorney.

Patented Jan. 10, 1933 1 UNITED s'r'res like HAROLD T. IIYMAN, JR., F SGHENECTADY, NEW YQRK, ASSIGNOR Ti} ELECTREC COIVXPANY, A CQR'EOEATIQN' OF NEW 1 031 ELEGTRIG' EEGULATQPJ Application filed April 1?,

My invention relates to apparatus for regulating an electrical condition of an alternating current circuit and more particularly to an electricalregulating apparatus utiliz- 6 ing electric valves which is particularly suitable for regulating the voltage of an alternating current feeder circuit,

Heretofore there have been devised numerous arrangements for regulating the voltage or other electrical condition of an alternating current circuit. Certain of these arrangements involve the use of contacts and other moving parts which tend to become unreliable in operation and are subject to wear and other T6 deterioration in use. Certain other regulat ing apparatus have been devised utilizing electric valves for edecting the desired regulation. Examples of this latter typeare dis? closed and claimed in the copending appli so cations of A. Boya'jian, filed April 17, 1931, Serial No. 530,880, Alan S. Fitzgerald, filed April 17, 1931, Serial No. 530,895, and G. V]. Garman filed April 17, 1931, Serial No. 530,881, all assigned to the same assignee as the present application. My invention relates to th type of regulating apparatus disclosed in the above mentioned applications which broadly claim certain features oi the apparatus disclosed in this application.

It is an object of my invention to provide an improved regulating apparatus utilizing electric valves which is simple and economical in operation and by means of which any desired fineness of regulation may be secured.

it is another object of my invention to provide an improved regulating apparatus utilizingelectric valves in which any harmonics of current or voltage occasioned by the use of electric valves will be substantially suppressed from the regulated circuit.

In accordance with my invention 1 provide an alternating current circuit with a booster transformer and energize the primary winding of this transformer from an impedance bridge. Each oi two adjacent arms of this impedance bridge includes a pair of electric valves reversely connected in parallel and the conductivity of these valves is controlled by adjusting the phase relation between the anode potentials and the grid ed across the diagonal of the bridge from Serial no. teases.

.cuit while the booster transformer is energized across the other diagonal. A filter circuit is associated with the impedance hridge for suppressing the harmonics due to the-use of phase control of the grid potentials of the electric valves.

For a better understanding of my inven-= tion together with other and further objectstliereof, reterence is had to the following description taken in connection with the ac-= ccmpanying drawing and its scope will he pointed out in the appended claims. Fig. 1 of the accompanying drawing is a diagramma-tic representation of my invention as applied to an arrangement for maintaining con stant the voltage of an alternating current feeder circuit, while Fig. 2 is a simplified drawing of the power circuit. Referring now to the drawing, 1 have illustrated an apparatus for regulating the voltage of an alternating current load circuit energized'from an alternating current supply circuit 11. This apparatus comprises a 7 booster transformer 12 provided with a secondarywinding interconnecting the circuits and with a primary winding connected across one diagonal of an impedance bridge. The impedance bridge may be visualized more clearly by referring to the diagram oi Fig. 2. The impedance bridge comprises two adjacent arms made up of reactors l4 and 16, respectively, and two adjacentarms made up of a reactor13 and a pair of electric valves 17 and 18 reversely connected in parallel, and a reactor and a pair of electric valves 19 and 20 reversely connected in parallel, respectively, The electric valves 17 to 20 inclusive are each provided with an anode, a. cathode, and a control grid and may be of any of the several types well known in the art, although I prefer to use valves of the vapor electric discharge type in which the starting of current in a valve is determined by the potential on its control grid hut in which the current flowing through the valve can be interrupted only hyreducing its anode potential below the critical value. A capacitor 2i is connect" Fall lilll which the primary Winding of the transformer 12 is energized.

The grids of the electric valves 17 to 20 inclusive ma be controlled manually to produce the desned regulation, or they may be controlled automatically in response to variations in the voltage of the load circuit 10. For the sake of completeness, an automatic grid control circuit will be described, although this circuit comprises no part of my present invention but is disclosed and claimed in a copending a plication of A. S. FitzGerald and F. L. aines, Serial No. 530,888 filed April 17, 1931, assigned to the same assignee as the present application. This grid control circuit comprises in general a voltage responsive element for indicating a departure of the voltage of the feeder circuit from normal, a phase shifting device for controlling the phase angle between the grid and anode potentials of the electric valves, and means for actuating the phase shifting circuit in one direction when the voltage is high, in the other direction when it is low, and for holding it steady when the voltage is correct. The volta eresponsive element comprises a bridge 22 aving a pair of opposite arms 23 and 2%, which are preferably resistors having substantially zero current-re sistance characteristics, and apair of opposite arms 25 and 26 which are preferably resistance devices having very high curren resistance characteristics, either positive or negative, such for example, as ballast lamps examples of which are well known in the art. @ne diagonal of the voltage responsive bridge is energizedacross the load circuit 10, while the other diagonal is connected to the primary winding of a control transformer 2?.

In order to control the conductivity of the valves 17 to 20 inclusive, the grids of these valves are connected to their respective cathodes through oppositely connected secondary windings of grid transformers 28 and 29 respectively. The primary winding of grid transformer 28 is energized from a static phase shifting circuit comprising a resistor 30 and a saturable reactor 31 connected across the secondary winding of a'transformer 32, the primary winding of which is connected to the supply circuit IL The primary winding of transformer 28 is preferably connected between the electrical midpoint of the secondary winding of transformer 32 and the junction between the resistor 30 and reactor 31. Similarly, the primary winding of grid transformer 29 is energized from a phase shifting circuit comprising a similarly connected transformer 33, resistor 34 and saturable reactor 35. The reactors 31 and 35 are provided with saturating windings 36 and 37,

respectively, which are connected in series across the supply circuit 11 through an electric valve 38. The valve 38 is preferably of the high vacuum pure electron. discharge sistor 39 which is included in the circuit of the secondary windin of the control transformer 27 in series with a reactor 10 and a unilaterally conductive device, shown as a contact rectifier 41. A capacitor 42 may be connected in parallel to the resistor 39 to smooth out any ripples in the potential across it due to the flow of rectified current from the transformer 27. llhe reactor 31 is also provided with a second saturating winding l3 differentially wound with respect to the saturating Winding 36 and energized from the supply circuit 11 through a unilaterally conductive device, shown asa contact rectifier l4, and a resistor 45.

in explaining the operation of the above described apparatus the operation of the power circuit per so will be considered first.

Referring more particularly to Fig. 2, the twopairs of valves 17 and 18, and 19 and 20, re-

spectively, comprise the equivalent of two impedances, the magnitude of which is determined by the phase relation between the grid and anode potentials of the valves. For the purposes of explanation, it will be hssumcd that, initially, the potentials of the grids of the several valves lug their anode potentials by equal angles so that the effective impedance of the pair of valves 1'? and 18 is equal to the effective impedance of the valves 19 and 20. The reactors 13 to 16 inclusive are so proportioned that the impedance bridge, as a whole, is now balanced. Under these conditions no potential difference exists across the diagonal which is connected to the primary winding ofthe booster transformer 12 and the voltage of the load "circuit 10 will be equal to that of the supply circuit 11, neglecting the impedance drop through the series transformer 12. If, now, the voltage of the circuit 10 tends to drop, due to an increase in load or for any other cause, the grid potentials of the valves 17 and 18 will be advanced with respect to their anode potentials while the grid potentials of the valves 19 and 20 will be correspondingly retarded with respect to their anode potentials, i. e. the effective impedance of the valves 17 and 18 is decreased while that of the valves 19 and 20-is increased. lhe impedance bridge is now out of balance and the difference potential across its diagonal connected to the primary winding. of the booster transformer 12 will raise .17 to 20 inclusive, consists of a series of chopped half sine waves, that is, half sine waves with their initial portions deleted. The

result of this chopping of the sine wave of connectii the capacitor 21 across the diagonal 0 die impedance bridge in parallel to the v 'nding of transformer 12, the do of -e odd harmonics delivered to the loci circuit may he limited to a per- 1 niissi ole value. Electric valves 17 to inclusive in y he considered, for the purpose of eirplanation as larmonic generators which are loaded, in serieswith reactors l3 15, through three parallel circuits comprising refi spectively capacitor 21, reactors l4 and 16 and the primary winding of transformer 12. ll-lowever t e capacitor 2i odors virtually short circuit for the higher harmonics while the imped e other two parallel paths 20 becomes for these harmonics.

on he grid control circuit to t desire l regulation is as follows: responsive 2% normally is l r such a to ne. 13in upon the grid of in 38 of the control transformer $227 t i the resistor 39 rec nacitor serving merely sense i t the pples oi rectified current Electric Jalve 3o reiierahly has a negative grid potential characteristic that is, its full range of conductivity he obtained by "a grid potential within p edeternegative potent-i The d' erentially wound r er 3% a d is of an equ r s f resistor e valve 38: in the conctivity so so e oi the reac or fundamental frequency is to produce a numher of odd harmonics which, if allowed to flow into the load circuit 10, would'be highly objectionable it has been found that, lay

*atcd. now that A load circuit l9 is normal.

nee the bridge is u L hose re grid potentials the ads or the valves 17 to 20- inproper amount of hnclr or red. e transiiorrner 12 for ex isting conditions of the circuit lo. lit, now the voltageoii the circuit 10 should tend to drop, o an increase in load or for any other voltage responsive bridge 22 will hecornore nnhalanced so that a larger current will ow through resistor 39 from the control transformer 25? and n higher negative potential he impressed upon the grid of.

This

valve 38,

increase its impedance with the result that the phase of the potentials supplied from the consider the preferred embodiment oi same time, as the saturation of the core of reactor 31 is increased, its impedance will he decreased and the phase of the potentials applied to the grids of the valves 17 and 18 will be advanced with respect to their anode po tentials and the efi'ecti ve, impedance of these valves will he decreased. The impedance bridge is now unbalanced in such a direction s to energize the primary winding oi booster transformer 12 to bring the voltage of the load circuit 10 hack to normal, Uhvionslyy with an increase in the voltageoi load circuit alcove normal the reverseoperation will" take place,

l is l have described what l my invention, it will he obvious to those skilled in the art that various changes and modificatrons may he made without ole ar sing; i'rorn my invention and l, therefore in the pended claims to cover i. such changes modifications as fall wlain the true spirit scope of my invention,

hat claim as new and desire to secure Toy Letters Patent of the. United States is:

l. lin cornloination, alternating current supply circuit a load circuit an inn eel-once hridge including pair of electric Wives, means for controlling the potential. or said load circuit in accordance with the unha I of said bridge, and means i. conductivity of said val hination a l snpn y circuit, a load circni brie is two arms which each incrac'" electric valves reversely connected lei means for controlling the tential circuit in accordance to the 1 of said hri ,e, and conductivity of said combination alter ating; current supply circuit load circui n irnped bridge two adjacent arms or l elude a pair of electric valves revers nected'in parallel one diagonal sai being connected across one of said circtn ts means for controlling the potential of said load circuit in accordance with the u halance of said bridge and means for regulat the conductivity or said valves 4.. In combination an alternating current supply circuit a load circuit an impedance bridge including a pair or? electric valves one diagonal of said bridge being connected across said supply circuit booster transformer having secondary winding connected Toetween said supply circuit and said load circoil: and a primary winding connected across the other diagonal of sand bridge, and means for regulating the conductivity of sold valves,

Elli

5. In combination, an alternating current suppiy urem a, a load en-emt, an Impedance budge twe m3 acent arms of whlch each m elude 21 psi? 0 electric valves reversel cam-- necte. in parallel, one diagenal 0 f said ridge inciuding fizhe junetien between the two pairs 0f valves being connected across said supply circuit hamster transformer having esecenery Winding connected between said sup-v E ply eircazic MM sefl lend circmt em? 21pmmary winciing connected across the other (111- egenei 0f said bridge, a cepeeiter cennected' memes the East, mentienedl diegenel and means fer regufieting the eonoluefivity 01 said waives:

I wimess whereez'f, I have hereume set my eesnee

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